[rnkjr]

I hope you noticed, my prior post was a Chat GPT response to your first post. With that being said, here is the Chat GPT response to your 11:51PM post: 1. How to do the AC voltage test on the distributor pickup

Your MSD distributor has a magnetic pickup, which produces a small AC signal that tells the MSD box when to fire the coil.

Where to test:
Unplug the two-wire magnetic pickup connector going into the MSD box.
It’s the violet and green wires.

How to test:

Set your multimeter to AC volts (not DC).

Put the meter leads on the violet and green wires.

Have someone crank the engine.

What you should see:

0.3 to 1.0 volts AC while cranking = pickup is good

0.0 to 0.2 volts AC = pickup is failing even if the ohms reading was normal

Heat can kill the signal even though resistance checks fine — that’s why this test matters.

2. What “voltage drop at the small red wire” means

The MSD 6AL has two power feeds:

Big Red = main battery power

Small Red = switched ignition power (what wakes the MSD box up)

If the small red wire loses voltage when hot, the MSD shuts off instantly, just like turning off the key.

Where to test:
Back-probe the small red wire at the MSD 6AL box (the small plug).

How to test:

Set meter to DC volts.

Put black lead to a good ground.

Touch red lead to the small red wire.

Check reading while cranking during the hot no-start.

What you should see:

11.5–12.5 volts = normal

Anything 10.5 volts or lower = MSD won’t fire

Voltage jumping, flickering, or dropping sharply = bad ignition feed or switch connector

This is a very common cause of random MSD shutdowns.

3. What to look for at the other connections
A. Big Red (main power)

Should have 12–12.6V key ON and 10.5+ volts while cranking.

B. Big Black (ground)

Should be bolted to clean metal, preferably the engine block or battery ground.
If in doubt, run a jumper cable temporarily from the MSD ground to the battery negative and see if the problem disappears.

C. Orange & Black at the Coil

You don’t need to measure voltage here yet — just confirm the connectors are tight and not corroded.

D. Yellow spade connector

If you only have one yellow spade, that’s normally the tach output.
If it’s tight, leave it alone — it doesn’t affect starting unless it’s grounding out.

The real goal of these tests

You already replaced coils, ignition switch, checked grounds, and the pickup ohms fine. The next step is to catch the system in the act when it’s hot and refusing to start.

One of these readings will be wrong only during the failure window, and that will tell you whether it’s:

the pickup signal disappearing

the small red ignition feed dropping voltage

or the MSD box itself breaking down from heat